Amateur Radio
Direction Finding
Amateur Radio Direction Finding (ARDF) — also known as Fox Hunting, T-Hunting, or Radio Orienteering — is an exciting blend of sport, technology, and strategy. In this fast-paced timed adventure, participants use directional antennas, radio receivers, and topographic maps to track down hidden transmitters scattered across parks, forests, and challenging outdoor terrains. It’s a test of skill, speed, and navigation that transforms radio science into a thrilling pursuit.
Introduction to ARDF
What is ARDF?
Amateur Radio Direction Finding (ARDF) — also called Fox Hunting, T-hunting, or Radio Orienteering — is a timed navigation sport. Competitors use a directional antenna, a radio receiver, and sometimes a topographic map to search for hidden radio transmitters in a park, forest, or other outdoor area.
Why ARDF?
- Each event presents a new challenge and develops navigation and technical skills.
- You can do it individually or with family and friends.
- Competitions are held at local, national, and world championship levels, with opportunities to win medals.
- No prior radio experience or Amateur Radio License is required to participate!
How Does It Work?
- Transmitters (called foxes) all operate on the same frequency, but take turns transmitting.
- Each fox transmits its unique signal for about 1 minute, then goes silent for up to 4 minutes while the others transmit in sequence.
- Competitors must take bearings with the receiver and antenna, navigate the terrain using map and compass, and plan an efficient route to visit all required transmitters in the shortest possible time.
ARDF combines the thrill of radio technology with the adventure of orienteering!
Insights about Transmitters, Centers and Participants
Amateur Radio Direction Finding (ARDF)
Amateur Radio Direction Finding (ARDF), also known as "fox hunting", particularly the formal, competitive version as practiced under IARU (International Amateur Radio Union) rules.
Transmitter (Tx) Signals and Identification
- Competitions occur on 3.5 MHz (80m band) or 144 MHz (2m band).
- Five hidden transmitters (called "foxes") transmit in sequence, each for 1 minute .
- Each has a unique Morse code ID:
- All start with "MO" (-- ---)
- Followed by a differentiating letter that has 1 to 5 dits (dots):
- MOE: -- --- . → 1 dot
- MOI: -- --- .. → 2 dots
- MOS: -- --- ... → 3 dots
- MOH: -- --- .... → 4 dots
- MO5: -- --- ..... → 5 dots
This makes identifying the Tx easy by counting the dots at the end.
Beacon Transmitter
- A 6th transmitter is always on (on a different frequency) transmitting "MO" (-- ---) continuously.
- It also denotes the finish of the hunt
Competition Rules
- Transmitter cycle: Only one Tx is on at a time, cycling every minute in a 5-minute loop.
- You use a direction-finding (DF) receiver to locate each Tx.
- Each found transmitter is marked with a red and white orienteering kite and a punch to stamp your control card.
Course Design Rules
Start and Finish are marked on your map. Transmitter locations are not.
Distance constraints:
- Tx must be ≥ 750m from the start.
- Tx must be ≥ 400m from the finish.
- Tx must be ≥ 400m apart from each other.
Your Goal as a Participant/Competitor
- Using your map and DF receiver, locate all 5 fox transmitters as quickly as possible.
- Punch your control card at each Tx.
- Return to the finish.
- You are scored on speed and number of correct transmitters found.
ARDF combines the thrill of radio technology with the adventure of orienteering!
Skills Developed
Radio Direction-Finding
Map Reading & Navigation
Strategy & Decision-Making
Fitness & Endurance